Which is to say: There was a period in which publishers were actively looking for "Big" books from new authors. They're now actively looking for small books -- as in short -- from new authors. (Keeping in mind that my last book was over 400,000 words, short for me would be the 140K that is currently the high end of acceptable new-author word count for the largest of the SF/F publishing houses).
There are many reasons (given) for this change, one of the largest having to do with production costs, and the P&L statement. Profit and Loss statements are done for each book at each publisher; I would guess that some of the details differ from house to house, but regardless, there are some base expenses that will be added to the cost side of the ledger. Cover art. Type-setting. Copy-editing. Printing costs. House overhead (which would be the percentage of the book's sale price that goes towards things like paying the rent, the utilities, the salaries of the editors/reps/etc). In order to keep costs -down- (and cover prices), one of the things that has to go down is page count.
When an editor wants to buy your book, she frequently has to discuss this with other editors or her superior in order to get permission to do so. Many factors will go into the decision, among those the possible profit or loss that the book will represent. Let's assume that the book is going to be bought. The editor phones, an initial offer is made, some (minor) negotiating occurs, and the contracts (three months later) are signed. You're on your way to being published. I've heard of offers from a major publisher that are as low as 1500.00 US for a mass market original paperback (again, SF/F); as high as 10K in other cases. I've also heard of higher, but on average, expect about 5K for a first book and you won't be heartbroken.
Editing occurs after the book is acquired, and the editing is generally done in three stages. The first is structural and substantive; the editor tells you what does -- and doesn't -- work for her, and why, and asks that these difficulties be addressed. After this is done, line-editing occurs. This isn't structural; it's sort of cleaning up, picking off excess words, duplicate words, repetitious phrases. Some authors -hate- this, some don't. I don't -- but if something clunks for me, I fix it. The last step would then be copy-editing, in which grammar, punctuation, and inconsistencies in the text ("you say there was a full moon here, but a week later, you mention the full moon").
A bad copy-editor is hell on earth. A good copy-editor is worth their weight in gold. You will have no choice in which of the two you get <wry g>. You won't have much choice in the cover, either. Or the cover blurb. You'll be sent cover flats (as reps call them) or cover proofs (as editors call them), and there will sometimes be little infelicities (typos, etc.) on those that you'll want to fix.
From this point, your cover flats will be put into kits that will be distributed to the sales force. The sales force are the men and women who will load up their cars with covers, catalogues, and ARCs (Advance Reading Copies) and travel around the country, showing the list for the season (or the month, depending) to buyers from both chain and larger independent stores. They'll take orders from those buyers, and send them back to the publisher. No, before you ask, most of the reps won't have read your book. They couldn't possibly read everything they're selling. They rely on editorial presentations (which used to be done in person, but are now mostly taped and sent in) and previous numbers of similar books, etc., for information.
The numbers in total that the sales force gets for your book -defines- the number of copies printed. It's interesting. In catalogues, a number for a first printing will often be stated (110K!), but that's so very theoretical, the only thing you can take from it is the publisher's sense of how well the sales force will be able to sell the book. If the orders that come in are, however, only 30K, the print-run will be something along the lines of 30K +percentage, usually between 10-20% depending on a number of factors.
Funny rep story: One of my sales reps, when I was buying, offered me a book that was just a ... turkey. It was in every possible way unappealing. It was supposed to be humourous. It was deadly dull. I looked at the first printing number in the book's information, and said, "In whose dreams?" and the rep said, "I've been told that I'm going to sell 10K of these." "In CANADA??" "Pretty much. Would you like to help me out by taking a few?" "Did you tell them that this sucks rocks?" "Me and every other person on the force."
This is funny, yes -- but illustrative as well. I'd seen the rep for three years. Had he tried to push it down my throat, I would have been actively annoyed, and for two reasons. 1: it was a turkey. 2: I was arrogant enough to assume that I had some idea of what would sell in my store, and had he really pushed me, it would not be unreasonable for me to assume that he was questioning my competence. The relationship between a buyer and a rep is one that has to last. There is some give
and take, and without question in my mind, a rep will get more books out there than simply putting catalogues in the mail will -- but the rep can't force someone to take a book he or she doesn't want. And it's not helpful for the rep to try.
It is not unreasonable for an author to be annoyed at how few copies the sales force has managed to get into bookstores; it is not -entirely- reasonable, however, to expect that the sales force can, in fact, get that book out everywhere.